<!doctype html>
<html>
	<head>
		<meta charset="utf-8">
		<title>飞机大战</title>
	</head>

	<body>
		<div id="stage" style="margin: 0 auto; width: 480px; height: 650px; text-align: center; vertical-align: middle" >
			<canvas id="canvas" style="border:0px solid red;" width="480" height="650">
				不支持画板对象
			</canvas>
		</div>
		<script>
			//把homework赋值为true。
			var homework = true
			//如果作业做完了，在警告框上显示“我帮妈妈做家务！”
			if ( homework ==true) {
				alert("我帮妈妈做家务！");

			}

		</script>
	</body>
</html>